The long-term objective of this project is to evaluate the ecological role of bacteriophages in the oral cavity and their significance in oral health and disease. Phages active against Actinomyces viscosus, a numerically important bacterium in human dental plaque, have been isolated characterized in this laboratory and the basic properties of their DNA genomes have been determined. With this information and purified viral DNAs available, the specific aim of this project is to apply modern methods of recombinant DNA technology and hybridization to develop viral nucleic acid probes which can be used to detect the presence of phage and phage genes in dental plaque and oral bacteria. The information gained by this study will also be directly applicable to future studies aimed at developing clinical diagnostic tests for specific viral and bacterial pathogens in the oral cavity.